AL GORE establishes his environmental credentials straight away in his global warming documentary An Inconvenient Truth. When he stands by a river, sees the leaves, feels the river bank give a little beneath his feet, hears a cow in the distance, he feels all gooey inside. This profound revelation sets the scene for his deeply manipulative movie. We first see the man who was almost the US president stride onstage to give a PowerPoint presentation claiming the global warming apocalypse is nigh. That presentation - boring graphs, pie charts, diagrams and all - is the movie, interspersed with footage of...